If you’re driving at 55 mph, you should not use the opposing lane to pass if you are within _________ of a hill or curve.

Explanation

You need about 10 seconds to pass in the opposing lane safely. Suppose you are driving at 55 mph and there is an oncoming vehicle also traveling at 55 mph that you cannot see because it is just behind a hill or curve. The two vehicles will close a distance of one-third of a mile in about 10 seconds. Therefore, if you move into the opposing lane to pass when you are within one-third of a mile of that hill or curve, you will be risking a head-on collision.